Re: [Xen-devel] [PATCH v4 04/10] xen/arm: set GICH_HCR_UIE if all the LRs are in use

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2014-03-19 at 12:31 +0000, Stefano Stabellini wrote:
> On return to guest, if there are no free LRs and we still have more
> interrupt to inject, set GICH_HCR_UIE so that we are going to receive a
> maintenance interrupt when no pending interrupts are present in the LR
> registers.

Should this go before the previous patch? Otherwise how to things work
between #3 and #4? This would be harmless to go in first I think, apart
from some spurious maintenance interrupts?

> The maintenance interrupt handler won't do anything anymore, but
> receiving the interrupt is going to cause gic_inject to be called on
> return to guest that is going to clear the old LRs and inject new
> interrupts.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> 
> ---
> 
> Changes in v2:
> - disable/enable the GICH_HCR_UIE bit in GICH_HCR;
> - only enable GICH_HCR_UIE if this_cpu(lr_mask) == ((1 << nr_lrs) - 1).
> ---
>  xen/arch/arm/gic.c |    6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
> index 32d3bea..d445e8b 100644
> --- a/xen/arch/arm/gic.c
> +++ b/xen/arch/arm/gic.c
> @@ -790,6 +790,12 @@ void gic_inject(void)
>          vgic_vcpu_inject_irq(current, current->domain->arch.evtchn_irq);
>  
>      gic_restore_pending_irqs(current);
> +
> +    if ( !list_empty(&current->arch.vgic.lr_pending) &&
> +         this_cpu(lr_mask) == ((1 << nr_lrs) - 1) )
> +        GICH[GICH_HCR] |= GICH_HCR_UIE;
> +    else
> +        GICH[GICH_HCR] &= ~GICH_HCR_UIE;
>  }
>  
>  int gic_route_irq_to_guest(struct domain *d, const struct dt_irq *irq,



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